1. Field of the Invention
The invention relates to a device for internal mass balancing in a self-reciprocating roll.
2. Description of the Related Art
DE 44 30 625 A1, to which U.S. Pat. No. 5,429,050 corresponds, discloses a gearbox configured for the transverse movement of a roll in a printing machine in such a way that a mechanism is provided which converts a relative rotational movement between the gearbox housing and an internal cylinder into an axial to-and-fro movement of the roll. The drawback with this configuration is that, as a result of this to-and-fro movement of the roll, forces are produced on account of the moving masses, and excite oscillations in the frame walls. It goes without saying that such an oscillation of the frame side walls is a hindrance to an optimum printing process.
The invention is based on the object of providing internal mass balancing in a self-reciprocating roll, a balancing weight being arranged in such a way that forces arising from the reciprocating movement and causing frame oscillations are eliminated by means of this balancing weight.
According to the invention, the object is achieved by a balancing weight arranged in the self-reciprocating roll to provide a force in a direction opposite to a roll reciprocating movement.
A significant advantage is that, as a result of the balancing weight, a force is generated which opposes the to-and-fro movement of the roll, eliminates the frame oscillations caused by this reciprocating movement and thus optimizes the printing process.
It is important that the entire device for internal mass balancing is fitted to a shaft of the roll. Such a constructional configuration of a device for internal mass balancing increases the multiplicity of the possible installations; thought should primarily be given to subsequent installation in self-reciprocating rolls already delivered to the customer.
If the balancing weight is mounted on the shaft of the roll, no drives for the balancing Weight are needed either, since the mass balancing is carried out with regard to a relative movement of the centres of gravity of the balancing weight and self-reciprocating roll.
A further variant of the device results from the balancing weight being assigned to the gearbox that executes a reciprocating movement of the roll. The preferred solution for internal mass balancing can be seen in this, since the balancing weight is moved in the direction opposite to the reciprocating movement of the roll, by means of a separate drive mechanism, which, as a significant advantage, still further increases the accuracy of the mass balancing. The mass balancing is carried out here by means of an absolute movement with regard to the position of the centres of gravity of the balancing weight and reciprocating roll.